Fast and Efficient Removal of Hexavalent Chromium from Water by Iron Oxide Particles

Abstract

Iron oxide particles (IOPs) were synthesized by chemical co-precipitation technique and further used as an adsorbent in removing hexavalent chromium (Cr(VI)) from aqueous solutions during batch adsorption. The IOP adsorbent had specific surface area of 65 m²/g, total pore volume of 0.25 cm³/g and mostly contained a mesoporous structure. The analysis of scanning and transmission electron microscopy indicated that the adsorbent contained a substantial amount of iron oxide of about 66%, which was well distributed throughout the adsorbent. The IOP adsorbent showed a rapid  and efficient Cr(VI) removal that followed Langmuir adsorption isotherm model with maximum adsorption capacity of 2.39 mg-Cr(VI)/g-IOP, demonstrating a monolayer formation on the adsorptive sites of IOP. The kinetic adsorption of Cr(VI) on the IOP followed the pseudo-second-order model, suggesting chemisorption. Thus, the IOP adsorbent provides a potentially effective technology in eliminating of Cr(VI) from water since it can remove appreciable amounts of Cr(VI) with a relatively short contact time of 30 min.